Making Electric Cars Noiser Harder Than Thought

We all originally thought we could create 'cartones' for our electric cars similar to ringtones for our phones. Turns out writing policy governing electric car noise generators is lot more complicated.

Published: 07-Feb-2015

Back in 2010, the U.S. Congress ordered the Transportation Department to formulate rules for automakers requiring their electric-drive vehicles make a sound to alert pedestrians and bicycle riders to their presence. Advocates for the blind were concerned that the cars are so quiet that pedestrians with impaired sight wouldn't know the cars were coming and would talk in front of them.

Now implementation has been pushed back to at least the third quarter of 2018, a decision that doesn't sit well with advocacy groups, especially as the number of electric-drive vehicles on the road continue to grow and more carmakers plan to introduce additional models going forward, the Kia Soul EV above being just the most recent model slated to hit showrooms.

As it turns out, the task of creating rules for electric-drive vehicle sounds is much more complicated than anyone ever thought, starting with: do these cars even need artificial sound generators?

Increasingly, luxury cars with conventional IC-engines can be demonstrated to be just as quiet at parking lot speeds, with most of the sound coming from the tires interacting with the pavement. Do the proposed rules only apply to electric cars and hybrids, which two National Highway Traffic Safety Administration (NHTSA) studies (2009, 2011) show are more likely to be involved in collisions with pedestrians and bicyclists? Or should they be applied across the board to any vehicle whose sound "signature" falls within the parameters spelled out by NHTSA?

Then there's the question of what the sound should be? Congress thought the sound "must be 'recognizable' as that of a motor vehicle in operation," writes Edmunds. But there are hundreds, maybe thousands of different engine types out there: four-bangers, economical sixes, powerful V-8s, even the rare three-cylinder and V-10.

Ultimately, what NHSTA did was select two reference sounds. You can listen to them here on NHTSA's Sample Sounds web page, as well as some of the 15 proposed sound solutions.

While the final rules won't appear now until 2018, carmakers aren't necessarily bidding their time. Nissan began addressing the problem early on, introducing the VSP or Vehicle Sound for Pedestrian system in its ground-breaking LEAF electric car. To hear what this sounds like, scrub forward in this second video to the 3:30 mark.

The Chevrolet Volt also incorporates a pedestrian alert system.

And while the wheels of U.S. bureaucracy turn ever so slowly, the pace of technological change may leave them behind was we start to see more remote vehicle sensing introduced. Models are already available to can detect obstacles in the road and their alert the driver or automatically stop the car. The more autonomous driving technology that gets introduced - and Cadillac is planning its first commercial system by 2016 - the less need they may be for external noise generators. It is and always has been the obligation of the driver to avoid the pedestrian.

In the case of cyclists, least three companies are working on innovative systems to avoid collisions here as well.

The simplest solution, of course, isn't technological at all. It's just good old common sense. Everyone of us, if we're walking, riding, driving, needs to be alert at all times to our surroundings, especially when we're in the close proximity to scores or hundreds of objects weighing several tons apiece and moving with the kinetic force of a freight train.

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